Orchard heaters

ABSTRACT

An orchard heater has sides of flame retardant material and base and cover of combustible material. The heater is filled with solid combustible composition eg. wax and the base and cover are so shaped that the heaters may be stacked vertically.

United States Patent Barnes et al.

[ 51 May 16, 1972 ORCHARD HEATERS Edward Barnes, Speldhurst; Kenneth H.Nance, Bromley, both of England Assignee: BP Chemicals Limited, London,England Filed: July 8, 1970 Appl No.: 53,103

inventors:

Foreign Application Priority Data July 8, 1969 Great Britain ..34,637/69Sept. 28, 1969 Great Britain ..52,7l3/69 U.S. CL... ...,.44/40, 126/595Int. Cl .A0lg 13/06 Field of Search ..126/59.5; 44/38, 40

[56] References Cited UNITED STATES PATENTS 3,338,691 8/1967 Knowles..126/59.5 UX 3,362,800 1/1968 Belak et a1. ..l26/59.5 X 1,047,13812/1912 McAdie ..126/59.5 3,105,484 10/1963 Goff 126/595 3,428,4102/1969 Johnston et a1 ..l26/59.5 X

Primary ExaminerCharles .l. Myhre AttorneyBrooks, Haidt & Haffner [5 7]ABSTRACT An orchard heater has sides of flame retardant material andbase and cover of combustible material. The heater is filed with solidcombustible composition eg. wax and the base and cover are so shapedthat the heaters may be stacked vertically.

10 Claims, 7 Drawing Figures ORCHARD HEATERS This invention relates toorchard heaters.

Growing crops and plants are subject to damage if exposed to periods ofcold weather. Thus orchards in particular may suffer considerable lossesin fruit production if subjected to frost at certain stages in thegrowth of the trees. It has been proposed to protect crops and plantsagainst frost damage by a variety of methods, none of which are entirelysatisfactory. U.K. Pat. Specification No. 1,126,014 discusses thesevarious methods and discloses a heater for use in the protection ofgrowing crops and plants which comprises a fire-resistant containerhaving an open end and containing a heating composition consisting of awax component and a buoyant particulate material. The heater preferablyhas a metal base.

The heater described above has a number of disadvantages. As it is openat the top, the filling is not protected from the weather, and thepossibility that some wax may get on to the outside surface of thecontainer, thus making handling more unpleasant and difficult, isincreased. Furthermore suppose it is found necessary to burn a heaterfor only a portion of its life during one period of cold weather, sayfor 4 hours out of an 8 hour life, and the next period of cold weatherrequires heating for 6 hours the person supervising the heaters mustvisit each three times in the course of the 6 hours; the first time toignite the partially spent heater, the second time to ignite a secondheater when the first has burnt out, and the third time to extinguishthe second heater. As the periods of cold or frosty weather generallyoccur at night, it will be readily understood that it would be highlydesirable to be able to eliminate the necessity to go to each heater andlight a new one when the first heater burns out. However although thesubject of protecting plants against frost has been studied for manyyears, no one has solved the problem of making orchard heaters which canbe burned individually and yet can be combined to burn one after theother in succession without further attention.

According to the present invention an orchard heater comprises acontainer containing a solid combustible composition, the side wall ofthe container being formed of a flame-retardent material the rate ofcombustion of which is lower than that of the solid combustiblematerial, the container having a base and cover of combustible material,the base and cover being so shaped that one container may be stackedvertically upon another.

By providing a cover and base the contents of the container areprotected against the weather, so that the heaters may if desired bestored in the open thus economizing on storage costs. By making thecover and base of combustible material and so shaped that the onecontainer may be stacked vertically upon another, the heaters can becombined to give total buming times in excess of the life of anindividual heater. This is achieved by stacking the heaters one abovethe other, the combustible base of one burning through to thecombustible cover of the one below, (which then burns through to ignitethe combustible composition underneath) when the upper heater burns out.It will be noted that the use of a cover and base more combustible thanthe flame-resistant side wall is in marked contrast to the prior artwhere if a base of material different from that of the walls is providedit is generally of metal or like non-combustible material.

It has been found desirable to provide the base and cover with raisedportions disposed so as to be in register when one container is placedupon the other. References to raised are to be considered in relation tothe operative position of the heater so that the raised portion of thecover will extend outwardly from the interior of the heater, while theraised portion of the base will extend upwardly, and thus extendinwardly that the design is so pronounced that as the uppermost heaterburns, part of the base becomes exposed, together with the correspondingpart of the cover of the lower heater, and burns so dropping anappreciable quantity of burning combustible material into the lowerheater unit.

Suitable materials of construction for the side wall include card orother combustible materials with an outer layer of non-combustible orslightly combustible material such as aluminum foil.

Suitable materials for the base and cover include polyethylenepolypropylene and polystyrene, a preferred material being unfilledpolystyrene.

Suitable solid combustible compositions include combustible waxes orfats which at normal temperatures are in a solid or semi-solid state,for example slack wax, paraffin wax and animal fats, and also oilssolidified by the addition of gelling agents or absorbed in a lowdensity absorbent material e.g. foamed styrene granules. By solidcompositions is meant a composition of such high viscosity that there isno risk of spillage in transport under normal conditions.

It is not necessary for heaters according to the present invvention tobe filled with a wick other than that which coincidentally occurs withthe construction of the container.

In use such a heater can be placed in a suitable position in an orchardwithout any further preparation and left through varying weatherconditions until required. When required it is only necessary to apply afierce igniting source such as a gas torch to the top of the unit, whenthe top cover will burn away quickly and the wax or similar materialbecome ignited and provide frost protection for a considerable number ofhours. As explained above one of the defects with existing heaters usingsimilar materials is that partially used candles must be lit for shortertimes. The heater of the invention, having a combustible cover and base,is so designed that a partially consumed and extinguished unit can beplaced on to a new unit after ignition. The partially consumed unit willburn down to its combustible base, through the top of the new unit, soigniting the new unit, which will then continue to burn in the normalmanner. It will be seen that this feature enables the most economic useto be made of heaters of this type and furthermore if very long frostsare expected or heating periods of a greater length than the life of oneheater are desired, two or more heaters can be stacked together andignited so as to give the desired length of heat production.

A further advantage of this construction of heater is that no dangerousresidues are left in the orchard or other area being heated which coulddamage mowers and similar tools which may be required in the cultivationprocedure, as is the case if heaters with metal bases are used.

The invention will now be further illustrated by reference to theexamples and the accompanying drawings in which FIG. 1 is a general viewof an orchard heater according to the invention, with the outer layer ofaluminum foil partly removed.

FlG. 2 is a cross section view of the orchard heater shown in FIG. 1,with the aluminum foil in place.

FIG. 3 is a general view of an orchard heater according to the inventionhaving a cover and base with raised portions.

FIG. 4 is a general view of another form of orchard heater having acover and base with raised portions.

FIG. 5 is a cross-sectional view of the adjacent parts of two orchardheaters as shown in FIG. 3 stacked one above the other in use.

FIG. 6 is another cross-sectional part view of the two orchard heatersshown in FIG. 5 in use.

FIG. 7 is a general view of a modified form of the lid fitted to theheater shown in FIG. 3.

The embodiment of the invention shown in FIGS. 1 and 2 was prepared bytaking a 7 X 7 inch sleeve 1 of 0.028-inch white line chip card 2covered with a layer of 0.009-inch thick laminated aluminum foil 3 andclosing one end of the sleeve by a base plate 4 formed from a sheet of0.0l5-inch thick unfilled polystyrene.

The box was filled with molten slack wax 5, allowed to cool andcompletely topped up with more molten wax to compensate for theshrinkage of the original quantity of wax on cooling. The heater wasthen closed with a lid 6 of the same material as the base. FIG. 3 showsan orchard heater made from the same materials as that shown in FIGS. 1and 2 except that the polystyrene cover 6 and base 4 are each providedrespectively with a continuous raised portion 7 and 8. The othernumerals have the same meaning as in FIGS. 1 and 2. When two heaters arestacked one above the other the raised portion 7 is in register withraised portion 8.

FIG. 4 shows an orchard heater made from the same materials as thatshown in FIGS. 1 and 2 except that the polystyrene base and cover isprovided with discrete raised portions or studs 8 and 7. The othernumerals have the same meaning as in FIGS. 1 and 2. The studs 7 aredisposed so as to register with the studs 8 when two heaters are stackedone above the other.

FIG. shows the lower part of one heater as shown in FIG. 3 resting onthe upper part of another heater according to FIG. 3. The wax 5 hasburned down to expose the upper parts 9 of the raised portion 8 of thepolystyrene cover. These portions rapidly burn through and ignited waxfalls through on to the wax in the heater below and ignites it. Theremainder of the base 4 and cover 6 burn away rapidly and the result isshown in FIG. 6 in which the lower heater is fully ignited.

The gap shown in FIG. 7 in the raised portion prevents rain wateraccumulating on the central portion of the lid when the heater is leftin the open.

It will be appreciated that a heater which is suitable for heatingorchards may also be useful for other heating purposes.

We claim:

1. An orchard heater comprising a container having a side wall, a base,and a cover, said container being filled with a solid combustiblematerial, the side wall being formed of a flame-retardant material therate of combustion of which is lower than that of the solid combustiblematerial, both the base and cover being formed of combustible materialwhich is more readily combustible than the material of said side walland so shaped that one container may be stacked vertically upon another.

2. The orchard heater according to claim 1 wherein the base and coverare provided with complementary raised and recessed portions disposed soas to be in register when one container is placed upon the other.

3. An orchard heater according to claim 2 wherein the raised portion isin the form of a repeating pattern.

4. An orchard heater according to claim 1 wherein the solid combustiblecomposition is a combustible wax or fat which is solid or semi-solid atnormal temperatures.

5. An orchard heater according to claim 4 wherein the solid combustiblecomposition is slack wax.

6. An orchard heater according to claim 2 wherein the solid combustiblecomposition is oil solidified by a gelling agent.

7. An orchard heater according to claim 2 wherein the solid combustiblecomposition is oil absorbed in a low density absorbent material.

8. An orchard heater according to claim 1 wherein the flame retardantmaterial is card covered with aluminum foil.

9. An orchard heater according to claim 1 wherein the base and cover arecombustible thermoplastic.

10. An orchard heater according to claim 9 wherein the base and coverare of unfilled polystyrene.

2. The orchard heater according to claim 1 wherein the base and coverare provided with complementary raised and recessed portions disposed soas to be in register when one container is placed upon the other.
 3. Anorchard heater according to claim 2 wherein the raised portion is in theform of a repeating pattern.
 4. An orchard heater according to claim 1wherein the solid combustible composition is a combustible wax or fatwhich is solid or semi-solid at normal temperatures.
 5. An orchardheater according to claim 4 wherein the solid combustible composition isslack wax.
 6. An orchard heater according to claim 2 wherein the solidcombustible composition is oil solidified by a gelling agent.
 7. Anorchard heater according to claim 2 wherein the solid combustiblecomposition is oil absorbed in a low density absorbent material.
 8. Anorchard heater according to claim 1 wherein the flame retardant materialis card covered with aluminum foil.
 9. An orchard heater according toclaim 1 wherein the base and cover are combustible thermoplastic.
 10. Anorchard heater according to claim 9 wherein the base and cover are ofunfilled polystyrene.